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chief
11-30-2005, 11:50 PM
I just finished a dicussion with a hot rod biker expert (you know the type," you can't make a part out of billet at home").
I told him that the bolt head( allen, hex, torx) has nothing to do with the bolt. I explained to him grade,pitch and class were what made a bolt. He stated Harley used toqx bolts to lessen vibration and loosening. I said they did it to sell tools.
I went so far as to offer to measure his bolt and compare it to some grade 8 allen head bolts I had. Any comments.

torker
12-01-2005, 01:05 AM
I think Harley uses them so when they get corroded and stuck, you can spin the innerds out of the bolt head with your Torx wrench...then you can't get it apart...then you have to buy a new bike http://bbs.homeshopmachinist.net//biggrin.gif
Hmmm...good marketing decision!

Automach
12-01-2005, 02:01 AM
He probably heard the phrase "torque to yield" and thinks it has to do with the bolt head shape.

Evan
12-01-2005, 02:13 AM
"I went so far as to offer to measure his bolt and compare it to some grade 8 allen head bolts I had. Any comments."

Yeah. Don't let him work on your bike.

larry_g
12-01-2005, 06:19 AM
Chief
Your correct in saying that the drive style of the head is not a factor in the holding power of the screw. (BTW the bit of bs factor here is that a bolt is designed to be torqued by turning a nut onto it and a screw is designed to be torqued by turning the head.) Torx drive heads are in fashion as they are a bit easier to handle with automated tooling and because most all of the drive styles are patented.
lg
no neat sig line

ahidley
12-01-2005, 07:21 AM
I just took an Evolution apart and the so called "head bolts" are not that. They were a nut about 2 inches long with a torx head. Kinda like a real long acorn nut. There was a stud mounted in the crankcase sticking up into the cylinders. So when viewing them assembled it looks like a screw head. But inescense its a nut.
I think the purpose for that, besides holding a precise torque, is that "joe harley mechanic" wont loose or strip one and go to the bucket of extra bolts in the shop and find a replacement that wont work properly.

charliechitlins
12-01-2005, 10:22 AM
I think torx is nothing more than the latest in the quest for a good-holding fastener that can be installed quickly in an assembly-line situation.
This was the original purpose of phillips and, probably, allen.
.
Fortunately, all 3 have a built in starter when you have to drill them because they are stripped. http://bbs.homeshopmachinist.net//wink.gif
None of them hold as well as the stalwart hex